Blower fans are presently commonly used for pushing, propelling, or otherwise circulating air. Normally, the air is circulated for cooling an area or for mixing the air at one temperature with air at another temperature located elsewhere i.e., mixing air near the ground with hot air which has risen near the ceiling.
Many different designs of blower fans have been made and are known to exist. Additionally, various different sizes of blower fans have been made and are known to exist. The larger transportable type of fans are, for example, three to six foot in diameter and are commonly used in large open areas, such as factories, football stadiums, and warehouses. Two of these types of prior art fans are shown in cross section in FIGS. 1 and 2. These typical blower fans, from the exterior, appear similar to that shown in FIG. 3.
The prior art fan shown in FIG. 1 includes an exterior cylindrical shroud 2, an intake disc-shaped grill or guard 4, an exhaust disc-shaped grill or guard 6, and wheels 8 rotatably affixed to shroud 2. In the prior art fan of FIG. 1, a motor 10 is attached to intake grill 4 and fan blades 12 are connected in driving engagement with the shaft of motor 10. The fan blades 12 are, thus, connected to the shaft of motor 10 in a cantilever fashion.
In the prior art fan shown in FIG. 2, unlike that of FIG. 1, an arbor 14 is provided and is attached to shroud 2 for supporting hub member 16. Arbor 14 can be a cross member intersecting at hub 16 wherein the cross members are at 90 degrees or 120 degrees from one another. Alternatively, arbor 14 can be merely vertical bars as, for example, shown in U.S. Pat. No. 4,239,459. Hub member 16, in turn, rotatably supports a shaft 18 having a pulley 20 at one end and the fan blades 12 at the other end. A motor 22 is attached to shroud 2 and drives pulley 24. Pulley 24 is in driving engagement with pulley 20 via belt 26 and, thus, fan blades 12 are also rotatably driven.
The prior art large blower fans, however, have shortcomings and drawbacks. Both prior art designs include a shaft whereupon the fan blades are mounted in a cantilever fashion. As a result, unless the shaft and the bearings thereof are increased in size, the life span is generally decreased. However, increasing the size of the shaft and the bearings increases manufacturing costs. Additionally, with respect to the prior art fan of FIG. 1, increasing the shaft and bearing sizes requires a special motor design thereby further increasing manufacturing costs. With respect to the prior art fan of FIG. 2, manufacturing costs are again increased in view of the additional material and labor required in providing the arbor and hub member combination for supporting the shaft.
Accordingly, a need exists for a blower fan construction that is both long lasting and inexpensive in terms of its material and labor costs.